Recovery of oil from contact clay



Patented June l9, 1 945 Standard Oil ration of Delaware Develop ment Company a corpo- No Drawing. Application MarchS, 194s,

, a serialnm vsa'zs 3 Claims-t The presentinvention is directed to therecovery of oils from pulverized clay or similar adsorbent bodies which have previously been contacted. with such oils to decolorizeorpurity them. More particularly theinventi'on is concerned with the recovery of petroleum lubricating oils from absorbent materials.

slurry to separate into a solid fraction and'a liq- .uid fraction. By proper selection of solvent and temperature it is possible to dissolve only the It is known to th art thatthe pulverized clays commonly employed for decolorizing and purifying lubricating oils retain. substantial amounts of lubricating oils. When these clays are discarded as spent, they may retain, on a dry basis, as. much as40% by .weightof high quality lubricating il invaddition to dark colored resinous material removed from the lubricating oils treated by the clay. Because of thel' qualityoil. adhering to the clay, attempts have heretofore beenmadeto recoverthe oil from the clay.

The conventional procedure for treating spent contact clay to recover lubricating oilstherefrom involvesadmixing with the spent contact clay a large volume of solvent of a. lower boiling range.

than the lubricating oil. Solvents such as petroleum ether gasoline, or non-viscous neutrals, may be admixed with the spent adheringto thespent contact clay. The admixarge amount of high clay in amounts ranging from 5' to times the volume of the oil miscible therewit good lubricating. oil. from the clay, leaving the resinous oilundissolved: or, it dcsiredyto dissolve all the oil adhering to thecIay; procedure may be modified if desired by employing two liqu-ids to form a slurry with thespent contactclay,

one of theli'quids. being. miscible with the lubrieating oil retained by the clay and acting as a solvent therefor, and the other liquid being im- The use of the miscible and immiscible. liquids together to form the slurry of the spent filter clay enables even larger amounts ofoil' to be recovered than when only a miscible liquid is used.

In accordance with the present invention a,

spent contact clay isadinixed with aliquid misslurry mud may then be subjectedto a mechanicible with the lubricating oil retained by the clay in the ratio of oil solublein the solvent to solvent ranging from 1:05 to 1:15. by volume. 'I;'he

cal pressure ranging from 50 to 3000pounds per ture may then be strained througha suitable filtering medium to separate the clay from the liquid fraction. It appears that the dilution of 5 the spent clay with oil and its subsequent filtration does not materially reduce the total amount of liquid retained by the clay, but a considerable portion of the more expensive lubricating oil is displaced by the less expensive solvent and is recovered. In addition, the solvent left on the clay may then be recovered therefrom by distillation.

It may be pointed out that one of the principal; disadvantages of this procedure is the necessity of removing the diluent from the recovered lubricating oil. This separating step carried out by distillation, and the large volume of diluent which must be evaporated from the recovered lubricating oil often involves the use of sovmuch energy as to make the process commercially unprofitable.

In accordance with the present invention lubricating oil is recovered from spent contact clay by admixing the clay with relatively small amounts of liquid capable of dissolving the lubricating oil to form a slurry or mud andsubsequently applying a mechanical pressure to the is customarily drainage of liquid square inch ina press arranged to allow the suitable press, for example, is one wherein a cylinder is jfitted with a screen at one end and a entering from the other end with means arranged for applying pressureto the piston. The solution pressed from the slurry by the mechanical pressure maythen be distilled to separate the solvent from th lubricating oil.

Particularly good results have been obtained by admixing not only a solvent with the spent contact clay in the amount abovestated, but in addition adding thereto a liquid immiscible in the oil i be subjected to be used repeatedly.

and in the solvent. The immiscible liquid is usually added to amounts within the range of the solvent present and forms a thick paste. This paste may then a mechanical pressure to separate a liquid phase from the clay and the liquid distilled to recover lubricating oil from the remaining liquid. It will, of coursefbe understood that the solvent is preferably recovered and may Liquids which are a ing oil and are suitable to act as a solvent in X practicing the present a and with the solvents slurry under conditions which will allow the 5s invention includes such materials as naptha, petroleum ether, benzol,ketones, esters or combinations of these various solvents. Liquids immiscible with lubricating oil asthe pressure is applied. A

the spent clay and solvent in miscible with the lubricatlisted above generally include water or aqueous solutions such asbrine,

alkali, or acid solutions. Generally because of its tion. In obtaining these results the clay slurry was placed in a cylinder fitted with a screen at the bottom and a plunger piston entering from the top. The pressure was applied slowly byforc ing the plunger downwardly-until the pressure indicated in the table had been reached.

current operation in which the solvent from one stage is used in another stage.

While the invention has been described with respect to recovery of petroleum lubricating oils from clay, it is within the spirit and scope of the present invention to recover other types of oil from absorbent bodies. I I

Having fully described the present invention, what I desire to claim is:

Y 1. A method for recovering lubricating oil from a contact clay previously employed for decolorizing lubricating oil by contact therewith comprising the steps of admixing said clay with a liquid solvent-forthe oil retained thereby in Table Analysis all): pressed 7 1 Y c e a Percent of Final pres- E L Treatment of clay prior to pressing sure, lbs./sq. ggg g gauge Ash, pergfi ggggi removed .cent d y e18 y 1 Sam 1e of spent clay from Sweetland ress 64. 6 0. 390 2 (a). ompressed to.1,000 lbs./sq.u1., (b flooded withwater H and re-com ressed 1,350 64.8 0.385 1.3 3 Pressed hot 200 F.) 3, 350 66. 6 0. 343 12. 1

- Pepared mud with 20% bywt. solvent and 80% spent 7 relay". 1, 000 70. 8 0. 258 33. 9 Prepared mud with 10% solvent and 90% clay (by wt.)' 500 69. 7 0. 276 29. 2 Prepared mud of water and spent clay 1, 000 64. 9 v0. 383 1. 8 Mud of 10% solvent and 90% clay, then mixed this with water to a thick paste" 500 71. 8 0. 233 40. 2

From the above table it willbe seen that very little'lubricating oil could be recovered from the spent clay merely by mechanically compressing the clay or even by flooding the filter cake with water and compressing it. It will also be evident that, although advantageous results are obtained by theadmixture of relatively small amounts of solvent with the spent clay and then mechanically compressing the slurry, even more satisfactory results are obtained when an immiscible liquid, such as water, is admixed with the solvent and contact clay before compressing the slurry.

It will be apparent to one skilled in the art that increased recovery over and above that obtainable in single stageoperation, as illustrated in the several examples, may be obtained in multiple stage operation or multiple stage counteramounts comparab1e'to, the amount of oil present in said clay and with a liquid immisciblein both said oil and. said solvent to form' a paste" and subsequently applying niechanicalpressure to said paste while withdrawing liquid therefrom inform a liquid fraction and a solid fraction and subsequently recovering lubricating oil from said liquid fraction,

2. A method in accordance with. claim 1 in which the ratio of lubricating oil present in the clay'to the "solvent is in the range of l :0.5'ito 3..,A method'in', accordance with claim 1 in which the solvent is petroleum ether and the liquid immiscible in both the lubricating oil and 

